Provided by: siggen_2.3.10-4_i386 bug

NAME

       swgen - a simple swept frequency signal generator

SYNOPSIS

       swgen [-2] [-s samples] [-8/-16|-b 8/16] [sweepwaveform]
              sweepfreq [sweptwaveform] minfreq maxfreq

       swgen [-2] [-s samples] [-8/-16|-b 8/16] [sweepwaveform]
              sweepfreq [sweptwaveform] centrefreq percent%

       waveform, either sweep or swept,
              is sine, cosine, square, triangle, sawtooth, noise

       for full list of options see below.

DESCRIPTION

       swgen  generates  a  swept  frequency  waveform  on  the LINUX /dev/dsp
       device. The swept and sweep waveform can be  seperately  specified,  as
       can  the  sweep  frequency  range  and  the  sweeping frequency.  Sweep
       frequency range can be specified either by giving the  minimum  (start)
       and maximum (end) frequency in Hertz; or by giving the centre frequency
       and the percentage frequency variation below and above. The  percentage
       is given as an integer value from 0 to 100.

       The  default sweep waveform is a sawtooth (ramp), and the default swept
       waveform is a sine. If the soundcard can do 16 bit samples, swgen  will
       do 16 bit by default.

       8 or 16 bit samples can be generated, in mono or stereo. In stereo, one
       channel carries the swept frequency signal, while  the  second  channel
       carries  the  sweeping signal. This can be useful fed to the X input of
       an oscilloscope when displaying frequency response curves etc.

       The samples can be written in raw or WAV format to files instead of  to
       the sound device.

       The  frequency  is specified as an integer number of Hertz.  Fractional
       Hertz frequencies are not supported. Of course, only  frequencies  less
       than half the samplerate (number of samples/sec) can be generated.

       The waveforms that can be generated are:

       sine   A standard sine wave

       cosine a sine wave with a 90 degree phase shift

       square a standard square wave with a 50% mark space ratio

       sawtooth
              a  ramp  waveform  with  'infinitely' fast flyback (:-) An ideal
              oscilloscope timebase signal.

       triangle
              shaped like equally spaced teeth on a saw (:-)

       noise  This is weak. All it  consists  of  is  one  second  of  pseudo-
              randomly  generated  samples,  played repeatedly. I'd love to do
              proper white/pink noise, but I don't know enough,  and  I  don't
              think  the  structure  of  the  program is conducive to accurate
              noise generation.

       swgen creates one second's worth of generated output in  a  buffer  and
       plays the buffer repeatedly, until it is terminated.

       A  lot  of  thought  has  gone  into  the algorithms for generating the
       waveforms.  I believe the sin/cos wave to be  very  pure  (modulo  your
       sound  card  :-), but I don't have access to a THD meter to measure it.
       For best signal accuracy NEVER use the gain  factor  option  (-A).  The
       generator  will then make the wave's peak value fit the maximum digital
       values allowed. Use a mixer program to control the output volume, or an
       external attenuator.

       The  gain  factor option can be useful for simulating a signal that has
       been subject to clipping. Specify a gain of > 100%. In fact a trapezoid
       signal can be made by generating a clipped triangular wave. The greater
       the gain, the closer the signal approaches a square wave (the rise  and
       fall times decrease).

       Defaults
              output  to  /dev/dsp, 22050 samples/sec, mono, 16 bit samples if
              possible, else 8 bit.

OPTIONS

       -h     display usage and help info

       -v     be verbose

       -f,-a  force overwrite/append of/to file.

       -C file
              use "file" as the local configuration file (see below).

       -o file
              write digital sample to file ('-' is stdout)

       -w file
              as '-o' but written as a WAVE format file. -a  (append)  is  not
              valid with this option.

       -s samples
              generate with samplerate of samples/sec

       -8/-16 or -b 8|16
              force 8 bit or 16 bit mode.

       -1,-2  mono (def), or special stereo mode (see above).

       -A n   scale  samples  by n/100, def. n is 100 (i.e. percentage of full
              scale output)

       -t N|Nm
              generate output for either N secs or Nm millisecs only.

       -x10 or -x100
              Scale frequencies down by a factor of 10  or  100.  This  allows
              fractional Hz values to be generated. See EXAMPLES below for its
              use. It is a Kludge.

EXAMPLES

       swgen -v 2 100 1000
              sweep a sin wave from 100Hz to  1000Hz  using  a  sawtooth  wave
              twice  a  second,  at 22050 samples/sec, 16bit samples on 16 bit
              card, 8 bit samples on an 8 bit card.

       swgen -v -s 44100 -w sweep.wav 2 100 1000
              as above but at a samplerate or 44100/sec and save one second of
              samples as a WAVE file in sweep.wav

       swgen -v -2 squ 10 1000 20%
              generate a sine wave switched by a 10Hz squarewave between 800Hz
              and 1200Hz.  The swept signal is on one  channel  and  the  10Hz
              square wave is on the second channel.

       swgen -v -x10 5 4400 4500
              generate  a  swept  sine  wave  from  440Hz  (4400/10)  to 450Hz
              (4500/10), being swept at a frequency of 0.5Hz (5/10). Yes  it's
              a  royal  pain remembering to scale all freqs. up by a factor of
              10, but I needed it in a hurry and didn't have  time  to  do  it
              better.

CONFIGURATION FILES

       Three  possible  configuration  files  can be used: a LOCAL config file
       (usually in current directory), a HOME  config  file  in  user's  $HOME
       directory and a GLOBAL config file.

       All  the  siggen  suite  of programs are compiled with the names of the
       config files built in. By default the configuration files are:

       ./.siggen.conf
              is the LOCAL config file.

       $HOME/.siggen.conf
              is the HOME config file.

       /etc/siggen.conf
              is the GLOBAL config file.

       swgen -h
              will indicate which config files will be searched for.

       The config files do not have to exist. If they exist and  are  readable
       by the program they are used, otherwise they are simply ignored.

       The  config  files  are always searched for configuration values in the
       order LOCAL, HOME, GLOBAL. This allows a scheme where the sysadmin sets
       up  default  config values in the GLOBAL config file, but allows a user
       to set some or all different values in their own HOME config file,  and
       to set yet more specific values when run from a particular directory.

       If  no  configuration files exist, the program provides builtin default
       values, and most of these values can be set by appropriate command line
       switches and flags.

       See siggen.conf(5) for details of the configuration files.

       swgen  looks  for  configuration  values CHANNELS, DACFILE, SAMPLERATE,
       SAMPLESIZE, VERBOSE.

       CHANNELS
              sets either mono or stereo mode like the '-1|-2' options.

       DACFILE
              allows the name of the DAC/DSP/PCM device  to  be  changed  from
              /dev/dsp

       SAMPLERATE
              sets the number of samples/sec for the DAC device

       SAMPLESIZE
              sets whether 8 or 16 bit samples to be generated

       VERBOSE
              sets whether or not to run in verbose mode.

SEE ALSO

       siggen.conf(5)

BUGS


COPYING

       Copyright 1995-2008 Jim Jackson

       The  software  described  by  this manual is covered by the GNU General
       Public License, Version 2, June 1991, issued by :

              Free Software Foundation, Inc.,
              675 Mass Ave,
              Cambridge, MA 02139, USA

       Permission is granted to make and distribute verbatim  copies  of  this
       manual  provided  the  copyright  notice and this permission notice are
       preserved on all copies.

       Permission is granted to copy and distribute modified versions of  this
       manual  under  the  conditions  for verbatim copying, provided that the
       entire resulting derived work is  distributed  under  the  terms  of  a
       permission notice identical to this one.

       Permission  is  granted  to  copy  and  distribute translations of this
       manual into another language, under the above conditions  for  modified
       versions,  except  that  this  permission  notice  may  be  included in
       translation instead of in the original English.

AUTHOR

       Jim Jackson

       Email: jj@franjam.org.uk